Synovial histopathology of psoriatic arthritis, both oligo- and polyarticular, resembles spondyloarthropathy more than it does rheumatoid arthritis

Alarmins in Frozen Shoulder: A Molecular Association Between Inflammation and Pain

BACKGROUND

The pathophysiological mechanisms behind proliferation of fibroblasts and deposition of dense collagen matrix in idiopathic frozen shoulder remain unclear. Alarmins (also known as danger signals) are endogenous molecules that are released into the extracellular milieu after infection or tissue injury and that signal cell and tissue damage.

PURPOSE

To investigate whether the presence of alarmins is higher in patients with idiopathic frozen shoulder than in control subjects.

STUDY DESIGN

Controlled laboratory study.

METHODS

Shoulder capsule samples were collected from 10 patients with idiopathic frozen shoulder and 10 patients with unstable shoulders (control). The samples were stained with hematoxylin and eosin (H&E) and analyzed by immunohistochemistry using antibodies against alarmin molecules including high-mobility group protein B1 (HMGB1), interleukin 33, S100A8, S100A9, and the peripheral nerve marker PGP9.5. Immunoreactivities were rated in a blinded fashion from "none" to "strong." Immunohistochemical distribution within the capsule was noted. Before surgery, patient-ranked pain frequency, severity, stiffness, and the range of passive shoulder motion were recorded and statistically analyzed.

RESULTS

Compared with control patients, patients with frozen shoulder had greater frequency and severity of self-reported pain ( P = .02) and more restricted range of motion in all planes ( P < .05). H&E-stained capsular tissue from frozen shoulder showed fibroblastic hypercellularity and increased subsynovial vascularity. Immunoreactivity of alarmins was significantly stronger in frozen shoulder capsules compared with control capsules ( P < .05). Furthermore, the expression of the alarmin molecule HMGB1 significantly correlated ( r > 0.9, P < .05) with the severity of patient-reported pain.

CONCLUSION

This study demonstrates a potential role for key molecular danger signals in frozen shoulder and suggests an association between the expression of danger molecules and the pain experienced by patients.

Role of the IL-23/IL-17 Axis in Psoriasis and Psoriatic Arthritis: The Clinical Importance of Its Divergence in Skin and Joints

Psoriasis is a chronic systemic inflammatory disease causing erythematosus and scaly skin plaques; up to 30% of patients with psoriasis develop Psoriatic Arthritis (PsA), which is characterised by inflammation and progressive damage of the peripheral joints and/or the spine and/or the entheses. The pathogenic mechanisms driving the skin disorder in psoriasis and the joint disease in PsA are sustained by the activation of inflammatory pathways that can be overlapping, but also, at least partially, distinct. Cytokines members of the IL-23/IL-17 family, critical in the development of autoimmunity, are abundantly expressed within the cutaneous lesions but also seem to be involved in chronic inflammation and damage of the synovium though, as it will be here discussed, not in all patients. In this review, we will focus on the state of the art of the molecular features of psoriatic skin and joints, focusing on the specific role of the IL-23/IL-17 pathway in each of these anatomical districts. We will then offer an overview of the approved and in-development biologics targeting this axis, emphasising how the availability of the “target” in the diseased tissues could provide a plausible explanation for the heterogeneous clinical efficacy of these drugs, thus opening future perspective of personalised therapies.

Targeting IL-17 in psoriatic arthritis

Psoriatic arthritis (PsA) is a chronic and progressive inflammatory arthritis intimately associated with psoriasis, and can be an impairing disease that leads to reduced quality of life and significant morbidity. Treatment often requires TNF antagonists, yet many patients with PsA are not responsive to the standard anti-TNF therapies. The interleukin-17 (IL-17)/IL-17 receptor (IL-17R) family has recently been implicated in the pathogenesis of PsA and psoriasis. Much enthusiasm has been generated for the development of biologics that target the IL-17 signaling pathway directly or indirectly, many of which have produced striking results in the setting of psoriasis and PsA. Herein, we review the role of IL-17 and the IL-17 receptor (IL-17R) in the pathogenesis of PsA, as well as the clinical evidence for IL-17 and IL-17R targeted therapeutics.

Power Color Doppler and Spectral Doppler Ultrasonography to Evaluate Response to Intra-articular Steroid Injection in Knee Joints in Juvenile Idiopathic Arthritis

OBJECTIVE

To evaluate the role of ultrasonographic indices (Color Fraction and Resistive Index) in assessing the effect of intra-articular steroid (IAS) injection on synovial inflammation in knee joints of Juvenile Idiopathic Arthritis (JIA) patients and to determine the correlation between these ultrasonographic indices and clinical and laboratory parameters in JIA patients after IAS.

METHODS

Twenty seven patients of JIA and equal number of age and sex matched healthy controls were enrolled. Thirty six knee joints were injected with IAS. Duration of morning stiffness, swelling score, tenderness score, range of motion, visual analogue scale for pain, Physician global assessment of disease activity, Patient/Parent assessment of general well being, Juvenile Arthritis Disease Activity Score, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), synovial thickness, synovial effusion, Color fraction (CF) and Resistive index (RI) were measured at base line and at one and two months of follow-up.

RESULTS

At baseline, a significant difference was found in ESR, CRP, CF and RI values between cases and controls. A significant decrease in various clinical, core set variables and ultrasonographic parameters was observed at each follow-up. Synovial thickness, synovial effusion and CF decreased by 51.78%, 64.67% and 49.35% respectively and range of motion and RI increased by 166% and 31.94% respectively at second follow-up. Both CF and RI showed a significant correlation with active joint count. Both CF and RI had a high inter and intra-class correlation.

CONCLUSIONS

Power Color Doppler and Spectral Doppler ultrasonographic indices (CF and RI) may have a role in assessment of the response to IAS injection of inflamed knee joints.

Angiogenesis Dysregulation in Psoriatic Arthritis: Molecular Mechanisms

There is evidence that psoriatic arthritis is closely linked to angiogenesis. Morphological changes described in blood vessels of psoriatic arthritis joints suggest the presence of a dysregulated angiogenesis resulting in the formation of immature vessels. Even if the reason of this inefficient angiogenesis is still unclear, an imbalance between angiogenic and antiangiogenic factors is probably responsible for inducing a dysregulated angiogenesis in psoriatic arthritis, which seems to be involved in its pathogenesis and clinical features. Nevertheless, among chronic arthritides, while angiogenesis in rheumatoid arthritis has been largely studied with a great amount of literature data, limited data on angiogenesis role in psoriatic arthritis are available. This review article is focused on current knowledge on the mechanisms responsible for dysregulated angiogenesis in psoriatic arthritis.

Bone mineral density in patients with psoriatic arthritis: data from the Nord-Trøndelag Health Study 3

Background

The risk of osteoporosis in patients with psoriatic arthritis (PsA) remains unclear. The aim of this study was to compare bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) in patients with PsA and controls.

Patients and methods

Patients with PsA and controls were recruited from the Nord-Trøndelag Health Study (HUNT) 3.

Results

Patients with PsA (n=69) and controls (n=11 703) were comparable in terms of age (56.8 vs 55.3 years, p=0.32), gender distribution (females 65.2% vs 64.3%, p=0.87) and postmenopausal status (75.6% vs 62.8%, p=0.08). Body mass index (BMI) was higher in patients with PsA compared with controls (28.5 vs 27.2 kg/m², p=0.01). After adjusting for potential confounding factors (including BMI), BMD was higher in patients with PsA compared with controls at lumbar spine 1–4 (1.213 vs 1.147 g/cm², p=0.003) and femoral neck (0.960 vs 0.926 g/cm², p=0.02), but not at total hip (1.013 vs 0.982 g/cm², p=0.11). Controls had significantly higher odds of having osteopenia or osteoporosis based on measurements of BMD in both the femoral neck (p=0.001), total hip (p=0.033) and lumbar spine (p=0.033).

Conclusion

Our population-based data showed comparable BMD in patients with PsA and controls. This supports that the PsA population is not at increased risk of osteoporosis.

Local effects of adipose tissue in psoriasis and psoriatic arthritis

The structure and physiological state of the local white adipose tissue (WAT) located underneath the lesional psoriatic skin and inside of the joints affected by psoriatic arthritis play an important role in the pathophysiology of these diseases. WAT pads associated with inflammatory sites in psoriasis and psoriatic arthritis are, correspondingly, dermal WAT and articular adipose tissue; these pads demonstrate inflammatory phenotypes in both diseases. Such local WAT inflammation could be the primary effect in the pathophysiology of psoriasis leading to the modification of the local expression of adipokines, a change in the structure of the basement membrane and the release of keratinocytes with consequent epidermal hyperproliferation during psoriasis. Similar articular adipose tissue inflammation can lead to the induction of structural modifications and synovial inflammation in the joints of patients with psoriatic arthritis.

A proof-of-concept study with the tyrosine kinase inhibitor nilotinib in spondyloarthritis

Background

To evaluate the immunomodulating and clinical effects of nilotinib, a tyrosine kinase inhibitor, in a proof-of-concept study in spondyloarthritis (SpA) assessing the mast cell as potential novel therapeutic target in this disease.

Methods

Twenty eight patients with active peripheral (pSpA) and/or axial SpA (axSpA) were included in a randomized, double-blind, placebo-controlled clinical trial (Trial registration: Trialregister.nl NTR2834). Patients were treated 1:1 with nilotinib or placebo for 12 weeks, followed by an open label extension for another 12 weeks. Paired synovial tissue biopsies, serum sampling and assessment of clinical symptoms were performed serially.

Results

In pSpA (n = 13) synovial inflammation appeared to diminish after 12 weeks of nilotinib treatment as evidenced by histopathology (decrease in number of infiltrating CD68+ and CD163+ macrophages and mast cells). Compared to placebo mRNA expression of c-Kit as mast cell marker (p = 0.037) and of pro-inflammatory cytokines such as IL-6 (p = 0.024) were reduced. The reduction of synovial inflammation was paralleled by a decrease in serum biomarkers of inflammation such as C-reactive protein (p = 0.024) and calprotectin (p = 0.055). Also clinical parameters such as patient’s global assessment of disease activity (p = 0.031) and ankylosing spondylitis disease activity score (p = 0.031) showed improvement upon 12 weeks of nilotinib but not placebo treatment. This improvement was further augmented at week 24. In contrast to pSpA, neither serum biomarkers of inflammation nor clinical parameters improved upon nilotinib treatment in axSpA. During the trial one serious adverse event occurred, which was considered unrelated to the study drug.

Conclusions

This small proof-of-concept study suggests that nilotinib treatment modulates inflammation and clinical symptoms in pSpA. A similar effect was not seen in axSpA.

Trial registration: trialregister.nl registration code NTR2834 registered 31 March 2011

Success Rate and Utility of Ultrasound-guided Synovial Biopsies in Clinical Practice

OBJECTIVE

The utility of synovial biopsy in increasing our understanding of the pathogenesis of inflammatory arthropathies, as well as in evaluating treatments, is well established. Ultrasound (US) allows synovial assessment and therefore assists in biopsying synovial tissue in a safe and well-tolerated manner. This study's objectives were to (1) determine the rate of success in retrieving synovial tissue using US guidance, (2) describe the indications for US-guided synovial biopsies in the clinical setting, (3) determine how frequently the synovial biopsy can lead to a clear diagnosis, and (4) assess the quality of the synovial tissue obtained using this technique.

METHODS

Synovial biopsies of small and large joints were performed under US guidance between February 2007 and December 2014 using a semiautomatic core biopsy needle. The biopsy procedure was considered successful if synovial tissue was found at histological examination.

RESULTS

Seventy-four patients with undifferentiated arthritis underwent 76 synovial biopsies. The success rate in retrieving synovial tissue was 81.6% (62/76). One patient taking acetyl salicylic acid at 75 mg at the time of the biopsy presented with hemarthrosis 48 h after the procedure, which resolved following simple arthrocentesis. A definitive diagnosis was achieved in 16% of the patients where synovial tissue was sampled successfully.

CONCLUSION

US-guided synovial biopsies in clinical practice can be performed safely on patients with undifferentiated arthritis and with heterogeneous presentations. The rate of success in acquiring synovial tissue is high. The procedure usually retrieves quality tissue and leads to a definite diagnosis in a significant minority of patients.

New therapies for psoriasis and psoriatic arthritis

PURPOSE OF REVIEW

Over the last several years, novel immunologic pathways pivotal in the development of the pathobiology of psoriasis and psoriatic arthritis (PsA) have been revealed. These discoveries catalyzed a search for new treatment targets resulting in many new therapies that are now available for patients with psoriatic disease.

RECENT FINDINGS

Helper T cells that secrete interleukin-17 (TH17) along with CD8+ cells, innate lymphocyte cells, and gamma delta T cells are important in the pathogenesis of psoriasis and PsA. Recently, agents that target interleukin-17, the interleukin-17 receptor, and interleukin-23 (antip19) have been approved or are in clinical trials. Apremilast, a new oral agent, was approved for the treatment of psoriasis and PsA.

SUMMARY

Secukinumab, an interleukin-17A antibody, has been approved for treatment of psoriasis and PsA in the United States. It is effective with a good safety profile. Ixekizumab, another anti-interleukin-17A antibody, is currently in clinical trials and brodalumab, an interleukin-17 receptor antagonist, was removed from clinical trials because of safety concerns despite demonstrated efficacy in psoriasis and PsA. Targeting interleukin-23 with antibodies to p19 is another approach with encouraging results in psoriasis. Apremilast, an oral agent, approved to treat psoriasis and PsA demonstrates moderate efficacy with an excellent safety record. The role of tofacitinib in psoriatic disease remains to be determined pending a safety review in psoriasis and completion of PsA trials.

Comparative effectiveness of biologic monotherapy versus combination therapy for patients with psoriatic arthritis: results from the Corrona registry

Objectives

To characterise the comparative effectiveness of combination therapy (a tumour necrosis factor inhibitor (TNFi) and a conventional synthetic disease-modifying antirheumatic drug (csDMARD) such as methotrexate) and monotherapy (TNFi only) for psoriatic arthritis (PsA) from a large US registry.

Methods

The analysis included adult patients with PsA who were enrolled in the Corrona database (ClinicalTrials.gov, NCT01402661), had initiated a TNFi, were biologic naïve, and had a follow-up visit ≥90 days after drug initiation. The endpoints of the analysis were TNFi persistence (drug survival) and time to Clinical Disease Activity Index (CDAI) remission. All analyses were performed using propensity scoring, which were estimated using CDAI and patient sex, to control for channelling bias.

Results

Of 519 patients meeting the inclusion criteria (318 with combination therapy and 201 with monotherapy), the analysis population was 497 for TNFi persistence and 380 for time to remission. The difference between combination therapy (TNFi+methotrexate, 91% of patients; TNFi+other csDMARD, 9%) and monotherapy was not statistically significant for TNFi persistence (32 and 31 months, p=0.73) and time to remission (21 and 25 months, p=0.56). Predictors of TNFi persistence included Hispanic ethnicity (longer persistence), PsA duration (longer persistence), history of methotrexate use (shorter persistence), body mass index (shorter persistence) and disease activity (shorter persistence).

Conclusions

Patients with PsA from a large US registry experienced similar TNFi persistence on combination therapy and monotherapy. Prospective, randomised clinical trials evaluating the efficacy of combination therapy versus monotherapy would provide much-needed clarity on treatment options for patients with PsA.

Trial registration number

NCT01402661.

Optimal management of dactylitis in patients with psoriatic arthritis

Psoriatic arthritis (PsA) is an inflammatory arthropathy associated with cutaneous psoriasis, which is currently classified as a seronegative spondyloarthropathy. The presence of cutaneous psoriasis is important for correct and early diagnosis of PsA, because the onset of cutaneous lesions usually precedes the appearance of joint manifestation. Thus, dermatologists are able to detect the condition at its inception. PsA has several unique characteristics such as enthesopathy, dactylitis, and abnormal bone remodeling. In particular, dactylitis occurs on the easily observed sites such as digits, and is thus a significant indicator of PsA. It is important to observe not only the fingers but also the toes, because dactylitis involves both digits of the hands and feet. Recently, new ideas regarding the involvement of the interleukin (IL)-23/Th17 axis have emerged, and the dramatic effects of targeting therapies have highlighted the physiological roles of key cytokines such as tumor necrosis factor-α, IL-17A, and IL-23 in psoriasis. As recent insights are shedding light on the pathogenesis of PsA, understanding of the pathogenesis of dactylitis and enthesitis are also progressing. In this article, current views on the optimal management of dactylitis are discussed.

Immunopathology of synovitis: from histology to molecular pathways

Increased knowledge about pathological processes active in inflammatory joint diseases is needed to initiate personalized medicine based on targeted treatments in the future. The molecular and cellular pathways that are active during joint inflammation may differ between the various inflammatory joint diseases, between different patient subgroups within one disease, or even between different stages of the disease in a single patient. In this review, we evaluate synovial inflammation in terms of descriptive histopathology through to more functional studies on human synovial tissue inflammation in RA and SpA, in phenotypic subgroups of RA and SpA patients, and during the disease course of both diseases.

Differential Antigen-presenting B Cell Phenotypes from Synovial Microenvironment of Patients with Rheumatoid and Psoriatic Arthritis

OBJECTIVE

To study the qualitative and quantitative phenotypic changes that occur in molecules involved in antigen presentation and costimulation in synovial B cells from rheumatoid arthritis (RA) and psoriatic arthritis (PsA).

METHODS

The presence of HLA-DR, CD86, and CD40 in CD20+ cells was studied in RA synovium biopsies using immunohistochemistry and immunofluorescence. Expression was assessed by flow cytometry of the Class II molecules CD40, CD86, CD23, and CD27 on B cells from the synovial fluid (SF), with respect to peripheral blood, from 13 patients with RA and 15 patients with PsA. Expression of interferon-induced protein with tetratricopeptide repeats 4 (IFIT4) in immune-selected CD20+ cells from patients with RA was assessed by quantitative realtime PCR.

RESULTS

Infiltrating synovial RA, B cells expressed HLA-DR, CD40, and CD86. Increased expression of CD86, HLA-DR, and HLA-DQ in B cells from SF was found in patients with RA and PsA. HLA-DP was also elevated in rheumatoid SF B cells; conversely, a significantly lower expression was observed in SF from patients with PsA. CD40 expression was increased in SF B cells from PsA, but not in patients with RA. Interestingly, CD20 surface expression level was significantly lower in SF B cells (CD19+, CD138-) from RA, but not in patients with PsA. CD27 upregulation and CD23 downregulation were observed in synovial B cells in both pathologies. Finally, a 4-fold increase in IFIT4 mRNA content was shown in B cells from SF in patients with RA.

CONCLUSION

Synovial B cells from patients with RA and patients with PsA express different antigen-presenting cell phenotypes, suggesting that this cell type plays a dissimilar role in the pathogenesis of each disease.

Gene Expression Profiling in Peripheral Blood Cells and Synovial Membranes of Patients with Psoriatic Arthritis

Background

Psoriatic arthritis (PsA) is an inflammatory arthritis whose pathogenesis is poorly understood; it is characterized by bone erosions and new bone formation. The diagnosis of PsA is mainly clinical and diagnostic biomarkers are not yet available. The aim of this work was to clarify some aspects of the disease pathogenesis and to identify specific gene signatures in paired peripheral blood cells (PBC) and synovial biopsies of patients with PsA. Moreover, we tried to identify biomarkers that can be used in clinical practice.

Methods

PBC and synovial biopsies of 10 patients with PsA were used to study gene expression using Affymetrix arrays. The expression values were validated by Q-PCR, FACS analysis and by the detection of soluble mediators.

Results

Synovial biopsies of patients showed a modulation of approximately 200 genes when compared to the biopsies of healthy donors. Among the differentially expressed genes we observed the upregulation of Th17 related genes and of type I interferon (IFN) inducible genes. FACS analysis confirmed the Th17 polarization. Moreover, the synovial trascriptome shows gene clusters (bone remodeling, angiogenesis and inflammation) involved in the pathogenesis of PsA. Interestingly 90 genes are modulated in both compartments (PBC and synovium) suggesting that signature pathways in PBC mirror those of the inflamed synovium. Finally the osteoactivin gene was upregulared in both PBC and synovial biopsies and this finding was confirmed by the detection of high levels of osteoactivin in PsA sera but not in other inflammatory arthritides.

Conclusions

We describe the first analysis of the trancriptome in paired synovial tissue and PBC of patients with PsA. This study strengthens the hypothesis that PsA is of autoimmune origin since the coactivity of IFN and Th17 pathways is typical of autoimmunity. Finally these findings have allowed the identification of a possible disease biomarker, osteoactivin, easily detectable in PsA serum.

Diagnosing and treating psoriatic arthritis: an update

Psoriatic arthritis (PsA) is an inflammatory arthritis of uncertain pathogenesis, affecting approximately one in four patients with psoriasis. Onset of psoriasis typically precedes the development of PsA. Therefore, the dermatologist is ideally positioned to recognize the early signs and symptoms of PsA for diagnosis and subsequent treatment. The role of the dermatologist in early diagnosis and treatment is essential for preventing pain and functional disabilities, as well as the joint deterioration that accompanies progressive forms of PsA. Diagnosis of PsA is a key aspect of the clinical decision process for the dermatologist, as psoriasis plus PsA requires a different therapeutic approach from that required for psoriasis alone. Furthermore, PsA is associated with an increased risk of cardiovascular comorbidities that present significant health concerns. In this review, the pathogenesis and comorbidities of PsA are discussed. In addition, screening and imaging tools that aid in the diagnosis of PsA, as well as tools used for efficacy assessment, are reviewed. Available therapies are presented, with a focus on targeted biologics and emerging treatments.

The microbiome and psoriatic arthritis

Psoriatic arthritis is a chronic inflammatory joint disease, seen in combination with the chronic inflammatory skin disease psoriasis and belonging to the family of spondylarthritides (SpA). A link is recognized between psoriatic arthritis and inflammatory bowel disease (IBD). Environmental factors seem to induce inflammatory disease in individuals with underlying genetic susceptibility. The microbiome is a subject of increasing interest in the etiology of these inflammatory immune-mediated diseases. The intestinal microbiome is able to affect extra-intestinal distant sites, including the joints, through immunomodulation. At this point, evidence regarding a relationship between the microbiome and psoriatic arthritis is scarce. However, we hypothesize that common immune-mediated inflammatory pathways seen in the "skin-joint-gut axis" in psoriatic arthritis are induced or at least mediated by the microbiome. Th17 has a crucial function in this mechanism. Further establishment of this connection may lead to novel therapeutic approaches for psoriatic arthritis.

The IL-23/IL-17 axis in psoriatic arthritis

Psoriatic arthritis (PsA) is an immune-mediated chronic inflammatory disease, affecting both the skin and joints. Disease progression is associated with aberrant cytokine expression, and TNF blockade is the most successful therapy to date. However, not all patients are responsive to anti-TNF treatment, highlighting the need to better understand the cellular and molecular mechanisms that govern the disease. PsA associations with single nucleotide polymorphisms in IL23R as well as TRAF3IP2 (Act1), a molecule downstream of the IL-17 receptor (IL-17R), have linked the IL-23/IL-17 axis to disease pathology. Although both cytokines are implicated in PsA, a full picture of their cellular targets and pathogenic mechanisms has not yet emerged. In this review, we focus on the IL-23/IL-17 axis-elicited responses mediated by osteoclasts, keratinocytes and neutrophils. Expanding our understanding of the cellular and molecular mechanisms that dictate pathogenicity in PsA will contribute to developing novel treatment strategies to combat disease.

Decreased plasma levels of soluble CD18 link leukocyte infiltration with disease activity in spondyloarthritis

INTRODUCTION

Spondyloarthritis (SpA) comprises a group of diseases often associated with HLA-B27 and characterized by inflammation of the entheses and joints of the axial skeleton. The inflammatory process in SpA is presumably driven by innate immune cells but is still poorly understood. Thus, new tools for monitoring and treating inflammation are needed. The family of CD18 integrins is pivotal in guiding leukocytes to sites of inflammation, and CD18 hypomorphic mice develop a disease resembling SpA. Previously, we demonstrated that altered soluble CD18 (sCD18) complexes in the blood and synovial fluid of patients with arthritis have anti-inflammatory functions. Here, we study the mechanisms for these alterations and their association with SpA disease activity.

METHODS

Plasma levels of sCD18 in a study population with 84 patients with SpA and matched healthy controls were analyzed with a time-resolved immunoflourometric assay (TRIFMA). Binding of sCD18 to endothelial cells and fibroblast-like synoviocytes (FLSs) was studied with confocal microscopy. Shedding of CD18 from peripheral blood mononuclear cells (PBMCs) was studied with flow cytometry and TRIFMA.

RESULTS

Plasma levels of sCD18 were decreased in patients with SpA compared with healthy volunteers (P <0.001), and the lowest levels were in the HLA-B27-positive subgroup (P <0.05). In a multiple regression model, the sCD18 levels exhibited an inverse correlation with the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) (P <0.05), the level of morning stiffness (P <0.05), the Bath Ankylosing Spondilitis Metrology Index (P <0.05), the physician global assessment score (P <0.01), and the sacroiliac magnetic resonance imaging activity score (P <0.05). The mechanisms for these changes could be simulated in vitro. First, sCD18 in plasma adhered to inflammation-induced intercellular adhesion molecule 1 (ICAM-1) on endothelial cells and FLS, indicating increased consumption. Second, CD18 shedding from SpA PBMCs correlated inversely with the BASDAI (P <0.05), suggesting insufficient generation. CD18 was shed primarily from intermediate CD14⁺⁺ CD16⁺ monocytes, supporting the view that alterations in innate immunity can regulate the inflammatory processes in SpA.

CONCLUSIONS

Taken together, the failure of patients with SpA to maintain adequate sCD18 levels may reflect insufficient CD18 shedding from monocytes to counterbalance the capture of sCD18 complexes to inflammation-induced ICAM-1. This could increase the availability of ICAM-1 molecules on the endothelium and in the synovium, facilitating leukocyte migration to the entheses and joints and aggregating disease activity.

Local synovial engagement of angiogenic TIE-2 is associated with the development of persistent erosive rheumatoid arthritis in patients with early arthritis

OBJECTIVE

To examine the role of vascular endothelial growth factor (VEGF) and angiopoietin signaling in the diagnosis and disease outcome of patients with early arthritis.

METHODS

Fifty patients with early arthritis (disease duration <1 year) who had not been treated with disease-modifying antirheumatic drugs (DMARDs) were monitored prospectively and were classified at baseline and after 2 years as having undifferentiated arthritis (UA), rheumatoid arthritis (RA), or spondyloarthritis (SpA). All patients underwent arthroscopic synovial biopsy at baseline. Synovial expression of VEGF, VEGF receptor, angiopoietin 1 (Ang-1), Ang-2, TIE-2, and activated p-TIE-2 was evaluated by immunohistochemistry. Serum levels of VEGF, Ang-1, and Ang-2 were measured by enzyme-linked immunosorbent assay. Secreted products of macrophages stimulated with Ang-1 and Ang-2 were measured using a multiplex system.

RESULTS

Expression of Ang-1 was comparable between the patients with RA at baseline and patients with UA who fulfilled the criteria for RA over time (UA/RA), and it was significantly higher in patients with RA (P < 0.05) or UA/RA (P < 0.005) than in patients with SpA. TIE-2 and p-TIE-2 were more highly expressed in patients with RA (P < 0.005) or UA/RA (P < 0.05) than in patients with SpA. Ang-1 significantly enhanced the tumor necrosis factor-dependent macrophage production of cytokines and chemokines that are known to be elevated in the synovial fluid of patients with early RA. In RA, relative TIE-2 activation predicted the development of erosive disease (R(2) = 0.35, P < 0.05).

CONCLUSION

Local engagement of synovial TIE-2 is observed during the earliest phases of RA, suggesting that TIE-2 signaling may contribute to disease development and progression or may indicate an attempt to protect against these processes. Early therapeutic targeting of TIE-2 signaling may be useful in improving outcome in arthritis.

Differences in synovial fluid cytokine levels but not in synovial tissue cell infiltrate between anti-citrullinated peptide/protein antibody-positive and -negative rheumatoid arthritis patients

Introduction

Comparative data on synovial cell infiltrate and cytokine levels in anti citrullinated peptide/protein antibody (ACPA)-positive and ACPA negative rheumatoid arthritis (RA) patients are scarce. Our aim was to analyze synovial cell infiltrate and synovial fluid (SF) levels of cytokines in patients with RA according to the presence or absence of ACPA in serum.

Methods

A cross-sectional study in a single center including consecutive RA patients was performed. Patients were defined as 'ACPA negative' if serum was negative to two different ACPAs [second generation commercial anti-cyclic citrullinated peptide antibodies (CCP2) and chimeric fibrin/filaggrin citrullinated antibodies]. Parallel synovial tissue (ST) biopsies and SF were obtained by knee arthroscopy. Synovial cell infiltrate and endothelial cells were analyzed by immunohistochemistry and SF levels of Th1, Th2, Th17 and pro-inflammatory cytokines by Quantibody(R) Human Array.

Results

A total of 83 patients underwent arthroscopy, with a mean age of 55.9 ± 12 years, and mean disease duration of 45 months (interquartile range, IQR 10.8 to 122). 62% were female and 77% were ACPA positive. No significant differences were found in clinical variables, acute phase reactants, synovial cell infiltrate or lymphoid neogenesis (LN) between ACPA positive and negative patients. However ACPA positive patients had significantly higher levels of IL-1β, IL-10, IL-17 F and CC chemokine ligand 20 (CCL-20) than ACPA negative patients.

Conclusions

In our cohort of patients with RA no significant differences were found in synovial cell infiltrate or synovial LN according to ACPA status. However, ACPA positive patients had higher levels of T-cell derived and pro-inflammatory cytokines than ACPA negative patients. As systemic and local inflammation was similar in the two groups, these findings support a distinct synovial physiopathology.

The bacterial skin microbiome in psoriatic arthritis, an unexplored link in pathogenesis: challenges and opportunities offered by recent technological advances

The resident microbial community, harboured by humans in sites such as the skin and gastrointestinal tract, is enormous, representing a candidate environmental factor affecting susceptibility to complex diseases, where both genetic and environmental risk factors are important. The potential of microorganisms to influence the human immune system is considerable, given their ubiquity. The impact of the host-gene-microbe interaction on the maintenance of health and the development of disease has not yet been assessed robustly in chronic inflammatory conditions. PsA represents a model inflammatory disease to explore the role of the microbiome because skin involvement and overlap with IBD implicates both the skin and gastrointestinal tract as sources of microbial triggers for PsA. In parallel with genetic studies, characterization of the host microbiota may benefit our understanding of the microbial contribution to disease pathogenesis-knowledge that may eventually inform the development of novel therapeutics.

Role of IL-17 in psoriasis and psoriatic arthritis

The role of T cell subpopulations in human disease is in a transition phase due to continuous discovery of new subsets of T cell, one of which is Th17, characterized by the production of signature cytokine IL-17. In the last couple of years, many articles are coming out on the role of Th17 and its signature cytokine IL-17 in different autoimmune diseases like rheumatoid arthritis, psoriasis, psoriatic arthritis (PsA), SLE and multiple sclerosis. Psoriasis and PsA are immune-mediated diseases, affecting the skin and joints, respectively. Initially, it was thought that psoriasis and PsA were Th1-mediated diseases; however, studies in knockout animal models (IL-17 knockout mice) as well as human experimental data indicate that Th17 and its signature cytokine IL-17 have a critical role in the pathogenesis of psoriatic disease. Th17 cells have been identified from the dermal extracts of psoriatic lesions. Subsequently, our research group has substantiated this observation that Th17 cells are enriched in the papillary dermis of psoriatic plaques and in freshly isolated effector T lymphocytes from the synovial fluid of PsA patients, and we have reported that the majority of these CD4 + IL-17+ T cells are of memory phenotype (CD4RO(+)CD45RA(-)CD11a(+)). Recent reports also suggest that the synovial tissue in psoriatic arthritis is enriched with IL-17R, and its most well recognized receptor IL-17RA is functionally active in psoriatic arthritis. In this review article, we have discussed the role of IL-17 in psoriatic disease and have narrated about the novel IL17/IL-17R antibodies currently in preparation for its therapeutic uses in autoimmune diseases.

Prevalence and incidence rates of psoriatic arthritis in central Norway: data from the Nord-Trøndelag Health Study (HUNT)

Background

A wide range in the prevalence (<0.01–0.25%) and incidence (0.5–23.1/100 000) of psoriatic arthritis (PsA) is reported. The main objective of this study was to examine the prevalence and incidence of PsA in central Norway.

Method

The patients were recruited from the Nord-Trøndelag Health Study 3, a population study carried out in 2006–2008. All 94 194 inhabitants aged >20 years were invited and 50 806 (54%) responded. The study consisted of a questionnaire (Q1) and a brief medical examination. Q1 included questions if the persons suffered from psoriasis, rheumatoid arthritis (RA) or ankylosing spondylitis (AS). Patients with self-reported psoriasis further answered a specific questionnaire on psoriasis including a questionnaire concerning PsA. In order to identify patients with PsA we used the following criteria: Persons reporting they had or may have PsA; persons answering that they had psoriasis and RA; and persons answering that they had psoriasis and AS. Using this approach, 1278 patients were identified. Hospital files were evaluated by a rheumatologist according to a predefined protocol to verify the diagnosis of PsA.

Results

338 patients, 144 men and 194 women, were verified to have PsA. The prevalence of PsA was 6.7 (95% CI 5.9 to 7.4) per 1000 inhabitants >20 years with no significant difference between men and women. In the 9-year period of 2000–2008, a total of 188 patients were diagnosed with PsA, which give an incidence rate of 41.3/100 000 (35.8–47.6).

Conclusions

The prevalence of PsA in central Norway appears to be higher than previously reported. The reason for this is unknown and may include environmental factors, life style factors and genetic differences.

Psoriatic arthritis: phenotypic variance and nosology

Psoriatic arthritis (PsA) has been recognized as a distinct entity different from rheumatoid arthritis. Classification and phenotyping of PsA have progressed substantially since the first classification criteria of the disease were published in 1973 by Moll and Wright. The initial disease patterns described by Moll and Wright have been found to overlap and change over time. There has been controversy about whether these should be maintained or whether the phenotype of PsA should include peripheral and axial disease only. PsA is a multifaceted disease that can present as different clinical phenotypes: peripheral arthritis, axial disease, skin and nail disease, dactylitis, and enthesitis. Development of the high-sensitivity and high-specificity CASPAR criteria was the first step to conducting high-quality trials and observational studies in the field.

How to translate basic knowledge into clinical application of biologic therapy in spondyloarthritis

Spondyloarthritis (SpA) is a family of many diseases, and these diseases share some clinical, genetic, and radiologic features. The disease process in the spine at the beginning is spinal inflammation, in which TNFα is the principal cytokine involved. Therefore, the dramatic clinical and pathologic response of anti-TNFα therapy in SpA is based upon the presence of increased TNFα in synovial tissues and sacroiliac joints, which perpetuates chronic inflammation. The increased Toll-like receptors (TCR) 2 and 4 in the serum, peripheral blood mononuclear cells, or synovial tissues of ankylosing spondyloarthritis (AS) or SpA patients suggest that SpA is highly associated with innate immunity. Any drug including anti-TNFα blocker which can downregulate the TCR, infiltrated neutrophils, or CD163+ macrophages in the synovial tissue is the rationale for the management of SpA. Like rheumatoid arthritis, the increased TH22 and TH17 cells either in blood, synovial fluid, or synovial tissues were also demonstrated in SpA. Thus, TH17 and TH22 may be reasonable cellular targets for therapeutic intervention. Drugs (anti-IL6R or anti-IL6) which can reduce the binding of IL6 and IL6R to the cell surface may be beneficial in SpA. Many proteins are implicated in the new bone formation (syndesmophyte) or ankylosis in AS or SpA. The enhanced BMP and Wnt pathway will activate osteoblasts which promote the new bone formation. However, no drug including anti-TNFα can stop or prevent the syndesmophyte in AS. In summary, looking for new targeting therapies for either anti-inflammation (beyond anti-TNF) or anti-bone formation (including anti-TGFβ or PDGF) is warranted in the future.

Angiogenic and inflammatory properties of psoriatic arthritis

Psoriatic arthritis (PsA) is a chronic inflammatory arthropathy associated with psoriasis and included in seronegative spondyloarthropathy. PsA has several unique characteristics different from rheumatoid arthritis (RA), such as enthesopathy, dactylitis, and abnormal bone remodeling. As compared with synovitis of RA (pannus), proliferation of PsA synovium is mild and characterized by hypervascularity and increased infiltration of polymorphonuclear leukocytes in the synovial tissues. Angiogenesis plays a crucial role in cutaneous psoriasis, and several angiogenic factors such as vascular endothelial growth factor, interleukin-8, angiopoietin, tumor necrosis factor- α and transforming growth factor-β, are suggested to play an important role also in the pathophysiology of PsA. Further, IL-17 has various functions such as upregulation of proinflammatory cytokines, attraction of neutrophils, stimulation of keratinocytes, endothelial cell migration, and osteoclast formation via RANKL from activated synovial fibroblasts. Thus, IL-17 may be important in angiogenesis, fibrogenesis, and osteoclastogenesis in PsA. In this paper, roles of angiogenesis in the psoriatic synovium are discussed, which may strengthen the understanding of the pathogenesis of PsA.

Psoriatic arthritis

Psoriatic arthritis (PsA) is a chronic inflammatory spondyloarthritis that occurs in combination with psoriasis. The exact prevalence of PsA is unknown, and its pathogenesis has not yet been fully elucidated. Genetic, environmental, and immunologic factors have all been implicated. The appearance of arthritis might precede, succeed or occur concomitant with skin lesions. PsA is sometimes considered a benign form of arthritis, but it affects patient quality of life and also causes functional impairment. Up to 20% of affected patients exhibit extremely destructive and disfiguring forms of the disease, and PsA is associated with increased mortality. The treatment of PsA aims to provide relief from signs and symptoms of the disease, prevent structural damage to joints, improve patient quality of life and decrease mortality. The choice of treatment depends on the severity of clinical presentation. The use of immunobiological agents is restricted to cases that do not respond to conservative treatment.

Relationship between inflammation, bone destruction, and osteoproliferation in the HLA-B27/human β2 -microglobulin-transgenic rat model of spondylarthritis

OBJECTIVE

Inhibition of inflammation and destruction, but not of osteoproliferation, in patients with spondylarthritis (SpA) treated with anti-tumor necrosis factor raises the question of how these three processes are interrelated. This study was undertaken to analyze this relationship in a rat model of SpA.

METHODS

Histologic spine and joint samples from HLA-B27/human β(2) -microglobulin (hβ(2) m)-transgenic rats were analyzed for signs of spondylitis and destructive arthritis and semiquantitatively scored as showing mild, moderate, or severe inflammation.

RESULTS

In rats exhibiting spondylitis, mildly inflamed sections displayed lymphocyte infiltration in connective tissue adjacent to the junction of the anulus fibrosus and vertebral bone but not at the enthesis. Moderately inflamed tissue samples contained osteoclasts eroding bone outside the cartilage end plate. In sections from rats with severe inflammation, the cartilage end plate and underlying bone marrow were also affected. End-stage disease was characterized by complete destruction of the intervertebral disc and vertebrae, with ongoing infiltration. Osteoproliferation was not observed in samples from rats with no or mild inflammation, but was present at the edge of the vertebrae in sections with moderate inflammation and persisted during severe inflammation and end-stage destruction. Osteoproliferation occurred at the border of inflammation, at a distance from bone destruction. A strong correlation between the extent of inflammation, destruction, and osteoproliferation was observed. Sections from rats with arthritis displayed a similar pattern of synovial inflammation associated with bone destruction, and simultaneous but topographically distinct osteoproliferation starting from the periosteum.

CONCLUSION

SpA in B27/hβ(2) m-transgenic rats is characterized by destructive inflammatory pannus tissue rather than by enthesitis or osteitis. Destruction and osteoproliferation occur simultaneously but at distinct sites in joints with moderate to severe inflammation.

Why is biologic therapy useful in spondyloarthritis? Knowledge from synovial immunopathologic studies of spondyloarthritis

The pathogenesis of most rheumatic diseases remains unknown. It is believed that both genetic and environmental factors play a pivotal role in the development of synovial inflammation in rheumatoid arthritis (RA), spondyloarthritis (SpA) and osteoarthritis (OA). In the last two decades, there have been many immunopathologic studies on RA, SpA and OA, and the findings revealed different types of arthritis may also present different pathologic patterns. These included higher vascularity and increased infiltration with CD163 macrophages and neutrophils, but relatively low values for lining cell (LL) hyperplasia in SpA synovium. However, the increased LL hyperplasia, as well as CD1a+ cells and the presence of intracellular citrullinated protein were more prominent in RA than in SpA synovitis. Anti-tumor necrosis factor alpha (anti-TNFα) therapy can significantly reduce synovial LL hyperplasia, vascularity and mononuclear cells infiltration in the majority of RA or SpA patients. This may explain why clinically, arthritis patients can get significant improvement after TNFα blocker treatment.

Light and electron microscopic features of synovium in patients with psoriatic arthritis

INTRODUCTION

Few ultrastructural studies have been reported in psoriatic arthritis (PsA). The authors report a series of synovial biopsies with emphasis on patients with early disease to look for distinctive light (LM) and electron microscopic (EM) features of possible importance.

METHODS

The authors examined synovial biopsies obtained primarily by needle biopsy from 13 PsA patients using LM and/or EM. Sections from 12 patients were evaluated by LM for vascularity, synovial lining thickness, fibrin deposition, and inflammation via a semi-quantitative scale. Nine EM specimens were descriptively analyzed. Clinical, synovial fluid (SF), and radiographic characteristics were recorded.

RESULTS

Patients were mostly male, with mean disease duration before biopsy of 2.19 ± 2.60 years; 7 patients had arthritis for less than 1 year. All patients had peripheral arthritis, 2 had axial involvement. SFs disclosed predominance of polymorphonuclear leukocytes. LM demonstrated proliferation of synovial lining cells, lymphocyte and plasma cell infiltration, as well as dramatic clusters of small vessels in the superficial synovium. EMs showed more detailed vascular changes, including small, subendothelial, electron-dense deposits and scattered microparticles in vessel lumens and walls.

CONCLUSIONS

Prominent vascularity is confirmed as an important feature of some PsA. Vascular changes and other features, including the first EM demonstration of microparticles in PsA (identified as potent factors in other inflammatory joint diseases), are potential targets for therapy.

High frequency of inflammatory back pain and other features of spondyloarthritis in patients with rheumatoid arthritis

The aim of this study was to investigate the frequency of patients with rheumatoid arthritis (RA) who have inflammatory back pain (IBP) and meet the existing classification criteria for ankylosing spondylitis (AS) and spondyloarthritis (SpA). We included 167 patients fulfilling the ACR 1987 revised criteria for RA. After obtaining a medical history and performing a physical examination, standard pelvic X-rays for examination of the sacroiliac joints (SIJ) were ordered in all patients. A computed tomography (CT) or magnetic resonance imaging (MRI) of SIJ was performed in patients with suspected radiographic sacroiliitis and MRI of SIJ in those who have IBP but no radiographic sacroiliitis. IBP was defined according to both Calin and experts' criteria. The modified New York (mNY) criteria were used to classify AS, both ESSG and Amor criteria for SpA and ASAS classification criteria for axial SpA. There were 135 female and 32 male patients with a mean age of 54.8 years. The mean disease duration was 9.8 years. RF was positive in 128 patients (79.2 %) and anti-CCP in 120 patients (81.1 %). Twenty-eight patients with RA (16.8 %) had IBP (Calin criteria), and four (2.4 %) had radiographic sacroiliitis of bilateral grade 3. Three patients (1.8 %) fulfilled the mNY criteria for AS, 31 (18.6 %) ESSG and 26 (15.6 %) Amor criteria for SpA. Nine patients (five with MRI sacroiliitis) (5.3 %) were classified as having axial SpA according to new ASAS classification criteria. This study suggests that the prevalence of SpA features in patients with RA may be much higher than expected.